Method and arrangement for uniformly heating a band-shaped material



1961 J. E. H. WESTBERG ETAL 2,972,668

METHOD AND ARRANGEMENT FOR UNIFORMLY HEATING A BAND-SHAPED MATERIALFiled Sept. 25, 1957 INVENTOR5 Jay/71v 54 1c HI/AEV WESTEEFG ATTORNEYUnited States Patent NIETHOD AND ARRANGEMENT FOR UNIFORMLY HEATING ABAND-SHAPED MATERIAL Filed Sept. 25, 1957, Ser. No. 686,059

Claims priority, application Sweden Oct. 9, 1956 Claims. (Cl. 219-19) Ithas been proposed to produce material in band shape which require a heattreatment for their production by winding the material on a rollertogether with a heat-emitting hand, through whose heat emission thewhole roll is brought to the temperature required for the process.

In the application of these methods on rubber-like material there hasappeared to be risk of the creation of bubbles or porosity in thematerial owing to the fact that some solvent is'transferred during theprocess into gaseous form and remains in the material.

The present invention comprises a method, the application of which isfree from the said disadvantage. The method of uniformly heating aband-shaped material according to the invention is characterized in thatthe material is wound onto a roller together with a band adapted to emitheat, one or more pressure rollers being pressed during at least part ofthe process with simultaneous rotation against the material wound on theroller.

The invention also refers to an arrangement for performing the method,the arrangement being characterized by a roller for winding up thematerial thereon and by one or more pressure rollers adapted to bepressed with simultaneous rotation against material wound on the roller.

The invention yields an essential advantage in that, owing to the rolleraction, the material is additionally stretched in heated condition,which causes lengthening of the most heavily loaded fibres thereof andan equalization of the fibre loading. This etfect can be enhancedthrough braking of the pressure rollers. A material produced in thismanner Will therefore be substantially stronger than if the productionis performed in accordance with other, known methods. For instance, in aparticular case, a value was obtained for the tensile strength of aneoprene-impregnated nylon fabric vulcanized according to the inventionexceeding by 28% the value for the same fabric vulcanized according to aknown method.

The invention further makes possible a simple solution of the problem ofsupplying current to the heating band during its movement. By making thetwo ends of the band have no insulation and constructing the roller andthe pressure rollers of metallic material and with good contactproperties, the pressure rollers and the roller can serve to applycurrent to the band. The pressure of the pressure rollers against themain roller yields satisfactory current passage when the .uninsulatedends make contact with the current-carrying rollers.

A further problem whose solution in a simple way is facilitated by theinvention is the measurement of the temperature of the material Withoutusing any temperatore-sensitive member producing dents in the material.The temperature measurement suitably comprises measurement of theheating band temperature at the beginning of the process, when the bandhas a known temperature. Since the resistance increase of the band as afunction of temperature is known, it is possible to ascertain bymeasurement of the resistance when temperature obtains and control theheat supply accordingly.

An embodiment of the invention is described in the following inconnection with Figs. 1 and 2, Fig. 1 showing an end view and Fig. 2 aside view of the arrangement with the band-shaped material rolled on.

In the figures, 1 denotes the main roller on which the material 2 andthe heating band 3 are wound. Against the roll thus formed, pressurerollers 4 are pressed with the aid of pneumatic pressure cylinders 5 andlevers 6. The rollers are surrounded by an insulating cover 7, the airin which is held at the same temperature as the heating band by means ofheat radiators 8 and fans 9. Current is supplied to the rollers 1 and 4by means of sliding contacts 10 and 11 and the resistance of the band ismeasured with a measuring instrument 12. A driving device 13 for drivingthe main roller is adjustable with regard to speed and direction. Thepressure rollers can be braked by means of brake members 14 havingcontrollable braking moment.

At the beginning of a work cycle, the material and the; resistive bandare wound onto the roller 1 and the pressure rollers 4 are pressedagainst the roll thus formed. When the material has been wound on, thecover 7 is closed and current is supplied to the band 3 as well as theresistors 8. The instrument 12 yields continual information about thetemperature of the roller and the current through the resistor 8 isadjusted so as to make the air temperature Within the cover reach thesame value. When the desired working temperature has been reached, thecurrent supply to the band is interrupted and there is then supplied tothe resistors 8 only as much current as is required for maintaining theair temperature within the casing. When the heat treatment is finished,the band-shaped material and the heating band are wound oil? withsimultaneous cooling onto different rollers. The pressure exerted by thepressure rollers during the operation should be different for differentmaterials and can be varied by control of the pressure applied to thecylinders 5. If extraordinarily heavy stretching of the material isdesired, the brakes 14 are tightened.

What is claimed is:

1. Apparatus for uniformly heating band-shaped material comprising afirst roller mounted for rotation, a band adapted to emit heat and woundin inter-engage ment with said material in a plurality of turns on saidfirst roller, at least one second roller mounted adjacent said firstroller and in pressure engagement with said material, and means forproducing heat in said band.

2. Apparatus for uniformly heating band-shaped material comprising afirst roller mounted for rotation, a band adapted to emit heat and woundin inter-engagement with said material about said first roller, at leastone second roller mounted adjacent said first roller and in pressureengagement with said material, and means for producing heat in saidband, said band and at least one of said rollers being electricallyconductive, said band engaging said conductive roller, and saidproducing means including means for conveying electric current to saidconductive roller.

3. Apparatus according to claim 1 further comprising a casing in whichsaid rollers are mounted, and means for heating said casing.

4. Apparatus according to claim 3 further comprising means forcontrolling the temperature attained in said band, whereby a cooperativerelationship between said temperature and that in said casing can beattained.

5. Apparatus according to claim 2 wherein said second roller isrotatab-ly mounted, and means is provided for braking one of saidrollers at a predetermined time, whereby said material is furtherelongated.

6. A method of uniformly heating a band-shaped material, comprisingwinding said material together with a band adapted to emit heat onto afirst roller so as to form a roll thereon, pressure engaging said rollwith at least one second roller, and producing heat in said band Whilerotating said first roller with said roll formed thereon.

7. A method according to claim 6 wherein said band and at least one ofsaid rollers is electrically conductive, and heat is produced in saidband by passing electric current thereto through said conductive roller.

8. A method according to claim 6 further comprising heating the airsurrounding said material.

9. A method according to claim 8 further comprising controlling thetemperature attained in said band commensurate with that of said air.

10. A method according to claim 6 wherein said second roller is alsorotated and further comprising braking said second roller atpredetermined times to further elongate said material.

References Cited in the file of this patent UNITED STATES PATENTS1,275,785 Stratton Aug. 13, 1918 1,401,303 Baldwin Dec. 27, 19211,941,362 Newcomb Dec. 26, 1933 2,226,315 Mailander Dec. 24, 19402,525,356 Hoyler Oct. 10, 1950 2,556,008 Spalding June 5, 1951 2,589,777Collins Mar. 18, 1952 2,629,808 Ulmschneider Feb. 24, 1953 2,649,530Dietz Aug. 18, 1953 2,763,893 Hall Sept. 25, 1956

